[msfa program crash]

I can confirm this behaviour. When trying to load a flight, then all variants tend to randomly cause a CTD. This behavious appears to be quite random though, sometimes it crashes, then sometimes it loads the flight just fine. For me too, the A300 seems to be affected only after the recent update.  

[Constant systems lock up from FMS inputs]

I find this too. No reliable way to reproduce though. Once it happened when requesting ATIS from the ACARS menu. Another time when trying to insert a waypoint in the FPLAN. Every system would become unresponsive, although the simulator itself does not crash. 

[Is the pressurization system modelled?]

I find that during climb, the differential pressure increases into the red band, as cabin altitude remains at ground level. Manually changing the cabin altitude with V/S control does change the open/close indication of outflow pressure valves, but cabin V/S rate remains around 0. Both packs are on. Is there a glitch, or is the system not modelled?